Well! Killian shamelessly enjoyed the reaction - there was something distinctly erotic about watching your partner touch themselves, and that was why he gave himself a hand, pun intended. Besides, Hawke had enough to do (and he was doing it well) - and Hook was all for giving a theatrical show. Together, or as close as they could manage.
The look on his face was hazy, smug, but that telltale prickling sensation overcame him and he knew he was done for - eyes squeezed shut, everything tensed and was loud again, a whimpering shudder, spilling hot and sudden over his hand; there was something about being with a man, someone just as rugged as he was, that was intensely thrilling - reached all the right spots, literally, something no waifish one-night stand who laid there like plankton could accomplish.
He had to catch his breath, but it didn't seem possible. Good Lord.